The present invention relates to a production process and a purification process of a bisphenol monoester represented by the following formula (I): ##STR2## R.sup.1 is hydrogen or an alkyl of 1 to 3 carbon atoms, R.sup.2 and R.sup.3 independently of one another are each an alkyl of 1 to 5 carbon atoms, and R.sup.4 is an alkyl of 1 to 3 carbon atoms, an alkenyl of 2 to 4 carbon atoms or phenyl.
The bisphenol monoester represented by the above formula (I) is useful as heat deterioration inhibitors in production or processing of butadiene polymers such as butadiene rubber (BR), styrene/butadiene copolymer rubber (SBR) and styrene/butadiene block copolymer rubber or resin (SBS) or as stabilizers for various synthetic resins, for example, polyolefins such as polyethylene and polypropylene.
For production of the bisphenol monoester represented by the formula (I), there have been known a process which comprises reacting a bisphenol compound represented by the following formula (IV): ##STR3## wherein R.sup.1, R.sup.2 and R.sup.3 are as defined above, with a carboxylic acid represented by the following formula (VI): ##STR4## wherein R.sup.4 is as defined above, using a halogenating agent in the presence of a dehydrohalogenating agent (U.S. Pat. No. 4,562,281 and U.S. Pat. No. 4,774,274), and a process which comprises reacting an acid halide or acid anhydride derived from the carboxylic acid represented by the above formula (VI) with the bisphenol compound represented by the above formula (IV) in the presence of a basic compound such as an amine or a pyridine (U.S. Pat. No. 4,365,032 and U.S. Pat. No. 3,984,372).
The bisphenol compound represented by the above formula (IV) is generally produced by condensation reaction of an aldehyde represented by the following formula (II): ##STR5## wherein R.sup.1 is as defined above, with a dialkylphenol represented by the following formula (III): ##STR6## wherein R.sup.2 and R.sup.3 are as defined above.
However, since the above-mentioned known processes for producing the bisphenol monoester represented by the formula (I) use the isolated and purified bisphenol compound (IV), loss in dissolution is caused in isolation and purification of the bisphenol oompound, resulting in reduction of yield based on the dialkylphenol (III) and besides, much time is required for filtration and drying. Thus, the processes have not necessarily been satisfactory in production on an industrial scale.
Furthermore, for purification of the bisphenol monoester represented by the formula (I) there have been known a process according to which recrystallization is carried out using petroleum ether or n-hexane as described in Examples 11 and 12 of U.S. Pat. No. 3,984,372, and a process according to which a solvent such as toluene or N,N-dimethylacetamide used for the reaction is partially or completely distilled off and toluene or n-hexane is added to the residue to carry out purification as described in Examples of U.S. Pat. No. 4,365,032, U.S. Pat. No. 4,562,281 and U.S. Pat. No. 4,774,274.
However, these processes are not satisfactory in quality of the desired product because purification effect is low owing to the small difference between the solubility of the desired bisphenol monoester contained in the crude product to be purified and that of impurities. Furthermore, these processes are also not satisfactory in production on an industrial scale since production equipments become complicated when the solvent is to be recovered for economical reasons.